scholarly journals A Novel Control Strategy on Stable Operation of Fuel Gas Supply System and Re-Liquefaction System for LNG Carriers

Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8413
Author(s):  
Soon-Kyu Hwang ◽  
Byung-Gun Jung
Keyword(s):  
Control Strategy ◽  
High Efficiency ◽  
Control Strategies ◽  
Dual Fuel ◽  
Stable Operation ◽  
Fuel Gas ◽  
Environmental Requirements ◽  
Energy Efficiency Design Index ◽  
Typical Configuration ◽  
Gas Supply

Liquefied natural gas has attracted attention through an explosive increase in demands and environmental requirements. During this period, the Energy Efficiency Design Index (EEDI), which was adopted by the International Maritime Organization, expecting to significantly reduce CO2 from ships, has become an important key. It has triggered a change in use from steam turbine systems and dual fuel diesel electrics to high-efficiency main engines such as ME-GI engines to meet the EEDI requirements. However, since the ME-GI engines use 300 bar of fuel gas pressure, it is necessary to resolve problems of the pressure controllability and to prevent the reductions of the re-liquefaction amount caused by clogging of the lubricant mixed with the fuel gas during the compression. The purpose of this study is to propose a novel control strategy with a newly developed configuration for controlling the pressure so as not to trip the BOG compressors when the ME-GI engines are tripped, and for preventing a reduction on re-liquefaction amount. Unlike the typical configuration used in the current vessels, this proposal separately provides the fuel gas at 150 bar without lubricants to the re-liquefaction. In addition, three control strategies are proposed, depending upon the application of multi-controllers and the location of the pressure transmitters. A simulation was conducted to verify the efficacy of the proposed method, focusing on the controllability of the pressure and the re-liquefaction amount, in comparison with the typical configuration. As results of the simulation, the proposal showed excellent controllability without trips of the BOG compressors even in abnormal conditions and confirmed the great re-liquefaction performance.

Study on a global control strategy for rotation speed with different work states in variable-speed constant-frequency wind turbines

2011 ◽  
Vol 225 (7) ◽  
pp. 968-976 ◽  
Author(s):  
G Zheng ◽  
H Xu ◽  
X Wang ◽  
J Zou
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Control Strategy ◽  
Control Strategies ◽  
Stable Operation ◽  
Constant Frequency ◽  
Global Control ◽  
Control Rules ◽  
The Individual ◽  
And Control

This paper studies the operation of wind turbines in terms of three phases: start-up phase, power-generation phase, and shutdown phase. Relationships between the operational phase and control rules for the speed of rotation are derived for each of these phases. Taking into account the characteristics of the control strategies in the different operational phases, a global control strategy is designed to ensure the stable operation of the wind turbine in all phases. The results of simulations are presented that indicate that the proposed algorithm can control the individual phases when considered in isolation and also when they are considered in combination. Thus, a global control strategy for a wind turbine that is based on a single algorithm is presented which could have significant implications on the control and use of wind turbines.

Comparison of two control strategies for VSC-MTDC with wind farm

2021 ◽  
Vol 14 ◽  
Author(s):  
Congshan Li ◽  
Pu Zhong ◽  
Ping He ◽  
Yan Liu ◽  
Yan Fang ◽  
...  
Keyword(s):  
Power Control ◽  
Control Strategy ◽  
Voltage Stability ◽  
Wind Farm ◽  
Control Strategies ◽  
Wind Farms ◽  
Active Power ◽  
Stable Operation ◽  
Active Power Control ◽  
Dc Voltage

: Two VSC-MTDC control strategies with different combinations of controllers are proposed to eliminate transient fluctuations in the DC voltage stability, resulting from a power imbalance in a VSC-MTDC connected to wind farms. First, an analysis is performed of a topological model of a VSC converter station and a VSC-MTDC, as well as of a mathematical model of a wind turbine. Then, the principles and characteristics of DC voltage slope control, constant active power control, and inner loop current control used in the VSC-MTDC are introduced. Finally, the PSCAD/EMTDC platform is used to establish an electromagnetic transient model of a wind farm connected to a parallel three-terminal VSC-HVDC. An analysis is performed for three cases of single-phase grounding faults on the rectifier and inverter sides of a converter station and of the withdrawal of the converter station on the rectifier side. Next, the fault response characteristics of VSC-MTDC are compared and analyzed. The simulation results verify the effectiveness of the two control strategies, both of which enable the system to maintain DC voltage stability and active power balance in the event of a fault. Background: The use of a VSC-MTDC to connect wind power to the grid has attracted considerable attention in recent years. A suitable VSC-MTDC control method can enable the stable operation of a power grid. Objective: The study aims to eliminate transient fluctuations in the DC voltage stability resulting from a power imbalance in a VSC-MTDC connected to a wind farm. Method: First, the topological structure and a model of a three-terminal VSC-HVDC system connected to wind farms are studied. Second, an analysis is performed of the outer loop DC voltage slope control, constant active power control and inner loop current control of the converter station of a VSC-MTDC. Two different control strategies are proposed for the parallel three-terminal VSC-HVDC system: the first is DC voltage slope control for the rectifier station and constant active power control for the inverter station, and the second is DC voltage slope control for the inverter station and constant active power for the rectifier station. Finally, a parallel three-terminal VSC-HVDC model is built based on the PSCAD/EMTDC platform and used to verify the accuracy and effectiveness of the proposed control strategy. Results: The results of simulation analysis of the faults on the rectifier and inverter sides of the system show that both strategies can restore the system to the stable operation. The effectiveness of the proposed control strategy is thus verified. Conclusion: The control strategy proposed in this paper provides a technical reference for designing a VSC-MTDC system for wind farms.

Fuzzy Logic Control Strategy for an Extended-Range Electric Vehicle

2012 ◽  
Vol 220-223 ◽  
pp. 968-972 ◽  
Author(s):  
Ji Gao Niu ◽  
Su Zhou
Keyword(s):  
Fuzzy Logic ◽  
Electric Vehicle ◽  
Control Strategy ◽  
Fuzzy Logic Control ◽  
High Efficiency ◽  
Control Strategies ◽  
Vehicle Performance ◽  
Logic Control ◽  
Extended Range ◽  
Avl Cruise

This paper presents a Fuzzy Logic Control Strategy (FLCS) for an Extended-range Electric Vehicle (E-REV) with series structure. The control strategy design objective of the E-REV is fuel economy. Based on the State of Charge (SOC) of the battery and the desired power for driving, the power required by the vehicle is split between the engine/generator set and the battery by the FLCS. The engine can be operated consistently in a very high efficiency area and the SOC of the battery can be maintained at a reasonable level. Some standard driving cycles and two control strategies of Power Follower Control Strategy (PFCS) and FLCS were simulated with AVL-Cruise and Matlab/Simulink to analyze the vehicle performance. Some simulation results are compared and discussed: the FLCS indicates better performance in terms of fuel consumption.

scholarly journals Improved SVPWM Fault-Tolerant Control Strategy for Five-Phase Permanent-Magnet Motor

Energies ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4626 ◽  
Author(s):  
Liang Xu ◽  
Wenxiang Zhao ◽  
Guohai Liu
Keyword(s):  
Permanent Magnet ◽  
Control Strategy ◽  
Pulse Width Modulation ◽  
High Efficiency ◽  
Fault Tolerant ◽  
Control Strategies ◽  
Fault Tolerant Control ◽  
Open Circuit ◽  
Permanent Magnet Motors ◽  
Permanent Magnet Motor

Multiphase permanent-magnet motors have received a lot of attention in the past few years owing to the merits of high power density, high efficiency and high fault-tolerant capability. Particularly, high fault tolerance is very desirable for safety-critical applications. This paper proposes an improved space vector pulse-width modulation (SVPWM) fault-tolerant control for five-phase permanent-magnet motors. First, generalized five-phase SVPWM fault-tolerant control is deduced and analyzed based on single-phase open-circuit fault, thus obtaining various SVPWM fault-tolerant control strategies and yielding a greatly increased capacity to enhance fault-tolerant performance of motor. Then, an improved SVPWM fault-tolerant control strategy with increased DC bus voltage utilization and reduced current harmonics is proposed and compared with the traditional one. Last, effectiveness and superiority of the proposed control strategy is verified by both simulation and experimental results on a five-phase permanent-magnet motor.

scholarly journals Integrated Control of Hydromechanical Variable Transmissions

2015 ◽  
Vol 2015 ◽  
pp. 1-11
Author(s):  
Shujun Yang ◽  
Yong Bao ◽  
Xianzhi Tang ◽  
Xiaojuan Jiao ◽  
Deqing Yang ◽  
...  
Keyword(s):  
Control Strategy ◽  
High Efficiency ◽  
Control Strategies ◽  
Integrated Control ◽  
Range Shift ◽  
Heavy Vehicles ◽  
Shift Control ◽  
Speed Fluctuation ◽  
Variable Transmission ◽  
Stable Stage

A hydromechanical variable transmission (HMT) has advantages of continuous variation and high efficiency. So it is one of the ideal transmissions of heavy vehicles. The continuous speed varying process involves speed governing in range and range shift. Integrated control strategy of the HMT is proposed in this paper. The algorithm of the asymmetric saturated incremental proportional integral derivative (PID) speed control strategy in range and range shift conditions are derived. And this paper presents the range shift logic and range shift control strategies. A controller model is built in Matlab Simulink and cosimulated with the model of vehicle equipped with a two-range HMT. The HMT prototype hardware-in-the-loop simulation (HILS) platform of the integrated control strategy is built. The HILS results show that the range shift process is smooth and speed fluctuation does not happen. In the throttle stable stage, the engine speed is adjusted to the near optimal speed, and its change rules are in accordance with simulation results. The integrated control strategy is reasonable.

scholarly journals Performance Modeling and Analysis of a Single-Shaft Closed-Cycle Gas Turbine Using Different Operational Control Strategy

2020 ◽  
Vol 6 (2) ◽  
Author(s):  
Emmanuel O. Osigwe ◽  
Arnold Gad-Briggs ◽  
Dodeye Igbong ◽  
Theoklis Nikolaidis ◽  
Pericles Pilidis
Keyword(s):  
Gas Turbine ◽  
Control Strategy ◽  
Nuclear Reactor ◽  
High Efficiency ◽  
Control Strategies ◽  
Operating Conditions ◽  
Cycle Performance ◽  
Closed Cycle ◽  
Independent Control ◽  
Modeling And Analysis

Abstract In the last few years, one considerable factor for the viability and interest in the closed-cycle gas turbine (GT) systems for nuclear or conventional power plant application is its potential to maintain high cycle performance at varying operating conditions. However, for this potential to be realized, more competitive analysis and understanding of its control strategy are importantly required. In this paper, the iterative procedure for three independent control strategies of a 40 MW single-shaft intercooled-recuperated closed-cycle GT incorporated to a generation IV nuclear reactor is been analyzed and their performance at various operating conditions compared. The rationale behind this analysis was to explore different control strategies and to identify potential limitations using each independent control. The inventory control strategy offered a more viable option for high efficiency at changes in ambient and part-load operations, however, operational limitations in terms of size and pressure of inventory tank, rotational speed for which the centrifugal forces acting on the blade tips could become too high, hence would affect the mechanical integrity and compressor performance. The bypass control responds rapidly to load rejection in the event of loss of grid power. And more interestingly, the results showed the need for a mixed or combined control instead of a single independent technique, which is limited in practice due to operational limits.

SIS Design for Fuel Gas Supply System of Dual Fuel Engine based on Safety Integrity Level(SIL)

2012 ◽  
Vol 49 (6) ◽  
pp. 447-460 ◽  
Author(s):  
Nak-Won Kang ◽  
Jae-Hong Park ◽  
Choung-Ho Choung ◽  
Seong Na
Keyword(s):  
Supply System ◽  
Dual Fuel ◽  
Fuel Gas ◽  
Safety Integrity Level ◽  
Gas Supply

Researches on Electronic Control System of Diesel-CNG Dual Fuel Engine

2013 ◽  
Vol 860-863 ◽  
pp. 1754-1760
Author(s):  
Lei Yu ◽  
Qing Yang ◽  
You Tong Zhang
Keyword(s):  
Control System ◽  
Diesel Engine ◽  
Natural Gas ◽  
Control Strategy ◽  
Control Strategies ◽  
Dual Fuel ◽  
Engine Fuel ◽  
Electronic Control ◽  
Present Contribution ◽  
Electronic Control System

Natural gas has been one of the most important kinds of vehicle fuel since the discovery of abundant shale gas storage. Operating costs of diesel engine can be reduced by replacing diesel with diesel-CNG dual fuel. The present contribution is mainly about the electronic control system of diesel-CNG dual fuel engine. Hardware and software of the electronic control system were designed. Two control strategies named equivalent power control strategy and diesel-saving control strategy were put forward for different control targets. Furthermore, these two strategies were testified by experiments conducted on engine test bench. Results show that average natural gas replacement could up to 70%. Comparing with diesel engine, fuel consumption of diesel-CNG dual fuel engine can be reduced significantly and the power increases slightly also. Both power and economy performances of the engine are improved.

scholarly journals Efficient Control of a Three Phase Grid Connected PV System

2021 ◽  
Vol 297 ◽  
pp. 01012
Author(s):  
Hicham Bahri ◽  
Mohamed Bahri ◽  
Mohamed Aboulfatah ◽  
M’hammed Guisser ◽  
El malah Mohammed ◽  
...  
Keyword(s):  
Control Strategy ◽  
High Efficiency ◽  
Control Strategies ◽  
Dynamic Performance ◽  
Atmospheric Condition ◽  
Photovoltaic System ◽  
Voltage Source ◽  
Good Precision ◽  
Pv System ◽  
Three Phase

This paper presents a new control strategy of a photovoltaic system, which consists of a photovoltaic generator PVG coupled to a three phase load and three phase grid by a three phase voltage source inverter VSI without DC-DC converter. The controller is designed by using Backstepping method based on d-q transformation of a new model of the global system. The main goals of this control strategy are to achieve the maximum power point MPPT with very good precision and the unity power factor in level of the grid power flow. Mathematical analysis demonstrate the asymptotic stability of the controlled system and simulation results proved that the controller has achieved all the objectives with high dynamic performance in presence of atmospheric condition changes. Moreover, the proposed controller shows a very good robustness under system disturbance, which presents the most important advantage of this controller compared to the other control strategies. Furthermore, this controller can operate with a high efficiency with any kind of the load.

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